1. Field of the Invention
The present invention relates to a rolling bearing, and more particularly to a rolling bearing which has a contact type sealing member including two ends. When one end thereof is fitted into either an outer ring or an inner ring of the rolling bearing, the other end thereof is configured to contact either the outer ring or the inner ring into which the one end has not been installed.
2. Description of the Related Art
In many cases, the rotating shaft of a motor is rotatably supported by a pair of preloaded rolling bearings. There is a sealed-type rolling bearing, in which a sealing member is fitted in between an inner ring and an outer ring of such a rolling bearing in order to keep grease, lubricating oil, or the like and/or in order to prevent the ingress of foreign particles into a bearing space between the inner ring and the outer ring of the rolling bearing. Further, there is a sealing member of the rolling bearing in which the sealing member contacts a seal groove provided on an inner peripheral surface of the outer ring or an outer peripheral surface of the inner ring. As an example of such a rolling bearing, for example, Japanese Patent No. 3,358,879 (hereinafter referred to as the Patent Document) discloses a rolling bearing in which a lip of a contact-type sealing member (contact seal) slidingly contacts to a seal groove formed on an outer peripheral surface of an inner ring.
However, in the above-described rolling bearing, sliding occurs between the lip of the contact seal (sealing member) and a contact surface of the seal groove to which the lip contacts. Thus, depending on operational condition of the rolling bearing, a so-called “stick-slip” may occur at sliding contact portions of the lip and the seal groove. Therefore, the sealing member itself may vibrate during the rotation of the rolling bearing, so that this vibration may cause noises, which produce unpleasant seal noises. In special, rolling bearings for a blower such as miniature ball bearings are required to have superior quietness, and these foreign noises should be suppressed.
Thus, in order to solve such a problem, for example, the Patent Document discloses: 1) contacting the lip of the contact seal to the seal groove in a radial direction; 2) providing a vertical portion which is a part of the lip extending in a radial direction and which is located closer to the outer ring than the part contacting the inner ring is; and 3) setting the surface roughness of the seal groove to 1S to 6S, i.e., more roughened than a conventional seal groove. The Patent Document thus tries to avoid the stick-slip and prevent the occurrence of contact seal vibrations and seal screeching noises.